ABSTRACT
Evaporative moisture loss from product can be approxi-
mated by
m ¼ Z
k pwsaw pwaRH=100
@A (2)
The mass transfer coefficient, k, includes the effect of
any packaging and product skin resistance to mass
transfer and is often measured experimentally because
it can be difficult to estimate from first principles. The
product water activity and the water vapor pressure at
the surface temperature are also often difficult to esti-
mate because the product surface temperature is
unknown, highly variable, or complicated to measure
or predict.
